Frequently Asked Questions

Naming follows the UI language (compact labels):

• English: HRV / RHR
• Simplified Chinese: 心率变异性 / 静息心率
• Traditional Chinese: 心率變異性 / 靜息心率
• Japanese: 心拍変動 / 安静時心拍
• Korean: 심박변이 / 안정시 심박
• German: HRV / Ruhepuls
• French: VFC / FC repos
• Spanish: VFC / FC reposo
• Italian: HRV / FC riposo
• Units: bpm and ms stay Latin in every language.

• HRV: Heart Rate Variability — tiny timing differences between heartbeats.
• RHR: Resting Heart Rate — heart rate when you’re fully at rest.

Yes—same metrics. Each language uses a short local label for layout; the meaning stays the same.

We don’t measure psychological stress. We measure your physiological stress response. By analyzing autonomic nervous system activity (HRV and heart rate), we quantify how much load your body is carrying right now.

HRV (heart rate variability) is the tiny variation in time between heartbeats. It’s a widely used marker of autonomic nervous system health. Higher HRV usually means your body adapts and recovers better under stress.

It’s based on your personal baseline. We compare your current HRV with the comfort zone built from recent history: values inside the zone are usually everyday fluctuation; below the zone suggests you’re more drained; above the zone suggests better recovery.

When the system detects a “Struggling” stress level and your HRV is clearly below your usual comfort zone—near your personal low—it may remind you that your body could be working hard, and slowing down first may help.

We don’t score “mood.” We ask whether your body’s load has left *your* usual comfort zone. We build a personal model from roughly 30 days of HRV (and heart rate when appropriate), then adjust for time of day.

With little data, we stay conservative; clearer zone boundaries come as the baseline matures. One-off highs or lows don’t easily redefine what’s normal for you. A higher heart rate from stairs usually won’t flip you to high stress if HRV is still steady.

Status comes from the comfort zone first; the score is a continuous scale for trends. This isn’t a medical diagnosis—just a clearer read of whether you’re in a usual day, more drained, or recovering better.

The card shows your “comfort zone”—the range where you tend to feel more stable and close to a typical good day. Once your baseline is mature, HRV inside that zone is judged more conservatively as everyday status; only values clearly below or above can move into the extreme ends. Being outside the comfort zone is not a medical abnormality—it simply means you’re clearly away from your usual range.

Usually not. The algorithm first checks whether HRV has also clearly left your usual comfort zone. If HRV stays steady, a high heart rate is more likely just walking, climbing stairs, or exercise. Heart-rate influence is reduced in those cases to avoid false alarms.

Usually several signals need to show up together:

1. HRV is clearly below your usual comfort zone, even near your personal low;
2. Heart rate is also higher than usual, or your body feels under load;
3. The change isn’t just a very short everyday blip.

This helps reduce false alerts while still notifying you when your body truly seems taxed.

In most cases, yes—it often reflects better cardiovascular health and recovery capacity. But HRV is personal and should be read against your own 30-day baseline. A sudden jump far above your usual range can also be an unusual response to accumulated stress (like overtraining or illness). Steady improvement over time is the healthiest pattern.

1. Regular exercise: Moderate activity plus good recovery can raise HRV, but avoid overtraining.
2. Enough sleep: Aim for 7–9 hours with a consistent schedule.
3. Balance work: Avoid long stretches of overtime so your body has time to repair.
4. Balanced eating: Favor quality protein and healthy fats; limit high sugar/salt and oversized late dinners.
5. Limit alcohol and caffeine: Alcohol is especially hard on HRV; avoid caffeine later in the day.
6. Stay hydrated: Good hydration supports oxygen delivery and can positively affect HRV.
7. Meditation & mindfulness: Slow, deep breathing can rebalance the autonomic nervous system.
8. Time outdoors: Being outside can help regulate cortisol and melatonin.
9. Track trends: Keep watching in the app, and step in early when values trend down.

• Sandercock et al. (2005): Review of exercise effects on HRV.
• Javaloyes et al. (2020): Research on HRV-guided training prescriptions.
• Spiegelhalder et al. (2011): Statistics linking insomnia and HRV.
• Young & Benton (2018): Biomarker research on nutrition and physical/mental health.

Your personal baseline is a physiological model built from your recent HRV and resting heart rate data. It tracks your typical level, comfort zone, and less common personal highs and lows.

We first compute your personal comfort zone for the matching time of day from about the last 30 days, then fine-tune with heart rate. Once the baseline is mature, HRV inside the comfort zone usually stays in everyday status; clearly below the zone suggests more strain, and clearly above suggests better recovery.

To stay accurate, the system uses different thresholds based on how many days of data you’ve built up. New users can get an early baseline from basic samples, but judgments stay more conservative. As you use the app longer and gather more samples, the comfort zone becomes a clearer boundary for status.

The system compares your current value with the comfort zone:

1. In range: The value is inside the comfort zone—your more stable everyday state.
2. Below baseline: The value is below the comfort zone. For HRV, that often suggests more fatigue or higher load.
3. Above baseline: The value is above the comfort zone. For HRV, that often suggests better recovery or more ease.

Once the baseline is mature, the comfort zone follows your usual swings for that time of day—it isn’t one fixed width for everyone.

The comfort zone is a stable band based on your usual swings over about the last 30 days at the matching time of day. It isn’t a medical diagnosis line or a risk alert line. It simply helps you see whether your current HRV is close to your more stable everyday state.

It shows the HRV baseline center and precise zone the algorithm is using right now—not your latest measured HRV. Based on when samples occur, the all-day baseline shifts with your circadian rhythm: sleep periods usually lean more toward recovery, daytime more toward activity. The “all-day reference” below helps you see how far this dynamic zone has moved relative to your full-day average.

Not directly. Occasional high or low HRV values are common, so the system doesn’t rely on ordinary standard deviation alone. It also looks at the median, typical distribution, and robust spread. In short: the algorithm cares more about where you usually sit than treating one unusually high HRV reading as everyday status.

Yes. The system adjusts your baseline every day from your latest health samples, so it can adapt as your lifestyle or fitness changes.

The bedtime baseline on Sleep details looks at when you usually fall asleep over about the last 30 days—the same window as your personal baseline. You need at least 3 nights of evening sleep before it appears. Naps that start roughly between 6:00 and 18:00 aren’t counted. The Home sleep card, Sleep details, and sleep score all use this same bedtime baseline.

No. Bedtime baseline is your usual clock time for falling asleep. Week avg sleep is the duration for this 7-day week, averaging only days that have a record. Sleep duration is scored against the sleep goal you set—not against a historical average.

If you have fewer than 3 usable nights, or a personal baseline hasn’t been saved yet, Sleep details hides that card. That’s common in the first few days. Once more nights are recorded, it shows up on its own.

Switch in Settings → Calculation Mode. Both modes still use HRV as the main signal—not two unrelated algorithms.

1. Real-time mode (recommended): At rest, stress can refresh about every 6 minutes. It still ranks mainly from HRV, then folds in recent heart rate with a limited weight to nudge how tense or relaxed that reading feels. A briefly faster pulse won’t by itself jump you from “okay” to “rough.” If heart rate is too old next to that HRV sample, it’s ignored and scoring falls back to HRV only. Walking or workouts are not scored as stress.
2. HRV mode: Follows Apple Watch’s automatic HRV samples only (often every 2–5 hours). Heart rate can still be shown, but it is not used in the score.

Choose HRV mode for a steadier read; choose real-time if you want it more in-the-moment while you’re at rest.

To protect accuracy, no new data is produced when:

• You’re walking or moving frequently (unstable heart rate)
• A workout is being recorded
• The watch is in Low Power Mode
• The watch is locked or worn loosely
• You’re in high-motion situations like running or riding in a vehicle

Apple limits how often third-party apps can measure. The only practical option today is turning on AFib History in Apple Watch Heart settings, which can raise automatic sampling to about every 15 minutes (note: this uses more battery).

1. Open the built-in Mindfulness app on your watch → Breathe.
2. Set the duration to 3 minutes or more.
3. When finished, lock and unlock your iPhone once.
4. After about a minute, the app should receive the raw sample and update.

We recommend a 3-minute breathing measurement within 10 minutes of waking (before eating or vigorous activity). That best reflects your readiness baseline for the day.

Common reasons include:

• Too much movement during the measurement
• The watch was in Low Power or Sleep mode
• Measurements were too frequent in a short window and the system limited them

Consciously pacing your breath—especially lengthening the exhale—can activate the parasympathetic nervous system, lower heart rate, and raise HRV. That helps shift your body into a calmer physiological state and quiet anxious signals in the brain.

1. Deep Breathing (4-7-8): Helps with sleep and deeper relaxation.
2. Box Breathing (4-4-4-4): Supports focus; a pattern often associated with Navy SEALs.
3. Relaxing Breath (4-4): Quickly steadies everyday tension.
4. Snore Relief (5-6): Trains breathing muscles and supports steadier breathing.

Try to follow the in-app visual and haptic guidance when you can. If you feel short of breath or uncomfortable, shorten the phases a bit and ease back into the recommended rhythm as your body adapts. Consistency matters more than perfect length in a single session.

Stress currently supports 4 shortcuts: Start Breathing, Log a Glass of Water, Check Current Stress, and Log Mood. You can use them with Siri, the Shortcuts app, or other system entry points that support Shortcuts.

Try phrases like:

1. “Start breathing with Stress”
2. “Begin a breathing exercise in Stress”
3. “Log a glass of water with Stress”
4. “Add water in Stress”
5. “Check my stress with Stress”
6. “Ask Stress if I’m stressed right now”
7. “Log my mood with Stress”
8. “Record my mood in Stress”

Open the Shortcuts app on iPhone, tap “+” in the top right, search for Stress, and add Stress actions to your own shortcuts or automations—for example, open breathing before bed, remind yourself to log water after lunch, or check current stress in the morning.

Yes. When you use Start Breathing in Shortcuts, you can choose Relaxing Breath, Deep Breathing, Box Breathing, or Snore Relief. If you leave it unset, Stress prepares a breathing session using the default option.

It records 250 ml by default. In Shortcuts you can also choose 250 ml or 500 ml. Water logs are written to Apple Health, so Stress needs write permission for dietary water first.

Common causes include: Siri didn’t recognize the app name, you haven’t enabled Stress actions in the Shortcuts app yet, Health permissions aren’t on, or the device can’t write water data right now. Try opening Stress once, then search for Stress in Shortcuts. If water logging failed, check write access in Apple Health.

Apple keeps every raw sample, while we apply date-aware processing or select specific samples for display. The values we show still come directly from HealthKit’s original records.

Both numbers are right—they answer different questions.

• Home card: your latest reading today, with the time it was taken shown underneath. It answers “where am I right now.”
• Top of the details page: the average for that day, so a single unusual reading doesn’t skew the whole day.

Scroll down in the details to see every raw reading of that day. When you look back at a past day, both places show that day’s average, so the numbers match.

Same as HRV: both numbers are right, they just answer different questions.

• Home card: your latest reading today, with the time shown on the card. It answers “what’s my heart doing right now.”
• Top of the details page: the average for that day (the small “Day avg” label). A short spike from stairs or a workout won’t rewrite the whole day.

When you look back at a past day, both places show that day’s average, so the numbers match.

All third-party watch faces are limited by watchOS refresh budgets (a fixed number of updates per hour). Opening the app can force a sync.

Besides missing permissions, the most common reason is no raw data in the past 2 hours. Rest quietly, or take a manual measurement with Mindfulness.

A checkmark means we could read data from the last 30 days. Apple doesn’t let apps see whether *read* access is on, so a warning doesn’t always mean access is off—it can also mean nothing was recorded lately.

That’s especially common for:

• Workouts: if you haven’t logged a workout in the last 30 days (from Apple Watch Workout or another app), there’s nothing to read.
• Workout Route: only outdoor GPS workouts create a route. Indoor workouts, strength training, and workouts you add by hand usually have no route, so this item can stay empty even when Workouts has data. If Workouts is turned off for Stress in Health, routes can’t be read either.

To check access: Health app → your profile picture → Privacy → Apps and Services → Stress.

Open Settings → Feedback, choose a suggestion or issue, and submit it. We’ll review it carefully, and you can attach device info and logs. You can also reach us on our Xiaohongshu page, or email [email protected]. We’re a small team, so replies may take a little time.

Occasional delay is normal on watchOS. If it keeps happening: install Stress on both iPhone and Watch with visible data; turn on notifications in iOS Settings → Stress; enable alerts in App Settings; turn on Background App Refresh for Stress on iPhone and Watch; leave Focus / Low Power / Theater modes. Reinstall or restart the Watch if needed.

Install the Stress Watch app first, and use watchOS 10+. Prefer adding the complication directly on the Watch. If the iPhone Watch app misbehaves, remove the face and add it again from the Watch.

Complications refresh when the Watch app has fresh cached data. Open Stress on the Watch once, keep Background App Refresh on, and avoid Low Power Mode. After a new HRV/stress sample, unlock the iPhone so HealthKit can sync.

Open Stress on Apple Watch → Settings (or the face options entry) and pick a theme. Themes apply to Stress complications that support them.

Common causes: brand-new Watch without enough history, Watch and iPhone disconnected, Health access off, Focus/Low Power modes, or Background App Refresh off. Fix those and retry, or relaunch the Watch app.

In iOS Settings → Privacy & Security → Health → Stress, allow all categories. If it still fails, delete the iPhone app, restart the phone, and reinstall.

With few samples the app builds a cautious early baseline. Wear the Watch regularly for about two weeks so your personal comfort zone can stabilize—judgments get clearer as data grows.

Yes for reliable updates and notifications. Stress’s background work is light; keep it enabled for the app on iPhone and Watch.

Usually no. It relies on HealthKit samples Apple Watch already collects. Realtime mode uses heart rate more often and costs a bit more than HRV-only mode.

Membership follows your Apple ID—sign in with the same account and tap Restore Purchases. Health data stays in Apple Health / iCloud Health sync between your devices.

Allow network access and use the same Apple ID that bought Pro. If you changed App Store country/region, redownload with the original account.

App Store → profile → Subscriptions → Stress → Cancel Subscription.

Use reportaproblem.apple.com or App Store → report a problem. Refunds are reviewed by Apple; developers can’t process them directly.